1. Technical Field
Example embodiments of the present invention relate to a method of analyzing a wafer sample. More particularly, example embodiments of the present invention relate to a method of analyzing a wafer sample for detecting a weak point of a pattern in an exposure process to set up a desired margin of the exposure process.
2. Discussion of Related Art
Semiconductor devices are generally manufactured through repeatedly performing separate processes that include a deposition process for forming a layer on a substrate, a chemical mechanical polishing (CMP) process for planarizing the layer, a photo process for forming a photoresist pattern on the layer, an etching process for patterning the layer into a pattern having electrical characteristics using the photoresist pattern, an ion implantation process for implanting ions into predetermined portions of the substrate, a cleaning process for removing particles from the substrate, an inspection process for inspecting defects of the layer and the pattern, and the like.
As a design rule of the semiconductor device decreases, a margin of an exposure process in the photo process also decreases and a step of detecting a weak point of a photoresist pattern becomes more important. In the conventional method of analyzing a wafer sample, the photoresist pattern is prepared on the wafer sample having a plurality of shot regions where patterns are repeatedly transcribed, and then the wafer sample is inspected with a high precision to detect defects of the photoresist pattern. The defects of the photoresist pattern repeatedly detected relative to each shot region are considered as the weak points of the photoresist pattern, and then the margin of the exposure process is adjusted in accordance with the number of the detected weak points of the photoresist pattern.
With a determination reference obtained from the repeatedly detected defects of the photoresist pattern, the number of weak points and the margin of the exposure process are changed. The determination reference, however, may unfortunately vary in accordance with the users. Although the weak points of the photoresist pattern and the margin of the exposure process are analyzed by one user, a consistent determination reference of analysis may not be ensured because the user subjectively determines the determination reference. Furthermore, the step of detecting the weak points of the photoresist pattern and a step of ensuring the margin of the exposure process may not be automatically carried out because of the subjective determination of the user.